This is a personal decsion. I've done both riverside and balcony and find that I like the riverside better.
The balcony seating has room for about 15 I think and fills up fast. You are above New Orleans Square and dead center for the show. The desserts are more upgraded than the riverside seating. When we were there we had Black Forrest Cake, White Chocoate/Rasberry Cheesecake, fresh fruit kabobs (pineapple, watermelon and strawberries on a skewer), cheese and crackers, a pastry platter that had about 5 different choices, but all I had was a tart I guess which was shortbread dipped in chocolate then topped with berries, and finally beignets (fritters) with a dipping sauce that I couldn't quite figure out what it tasted like. We also had our choice of coffee, hot cocoa, soda and water, all served in very nice glass mugs or glasses. And you had real plates, utensils and cloth napkins.
The riverside seating is off center, but you still have a water screen in front of you and can see all the action. I like this better because you feel the show rather than just watch it. When we did the riversdie this past summer, we had the choice of Mickey shaped rice krispy treats, biscotti, chocolate dipped strawberries, shortbread cookies with jam inside, and brownies. The drinks were the same choices as the balcony, but this time the hot drinks were served in the same disposable cups as the rest of the park and the cold drinks were bottled. We were even encouraged to take some along with us after the show. We had paper plates and napkins, no utensils since it was all finger food.
I've heard that the riverside desserts were switched over to a box with assorted treats. And that's the answer I was given when I asked our hostess this past weekend (that's when we did the balcony.) But the official DL site still says buffet and I never went by the riverside seating to verify for myself.
Now that I've done both, I doubt that I will do the balcony seating again. Yes, the food was a little better, but I much prefer the riverside experience. You're just more involved in the show. Plus on the riverside you get a $10 break for kids.